A light emitting diode refers to an inorganic semiconductor device that emits light through recombination of electrons and holes, and has recently been used in various fields including displays, automobile lamps, general lighting, and the like. In particular, a nitride semiconductor such as gallium nitride, aluminum nitride, and the like has direct transition characteristics and can be manufactured to have an energy bandgap in various bands, thereby allowing manufacture of light emitting diodes configured to emit light in various wavelength bands, as needed.
A light emitting diode including a nitride semiconductor is manufactured through growth on a homogeneous substrate or a heterogeneous substrate. Since the homogeneous substrate is expensive and difficult to form in a large area, a heterogeneous substrate such as a sapphire substrate is generally used as a growth substrate for nitride semiconductors.
Recently, a patterned sapphire substrate (PSS) having a plurality of protrusions arranged on a growth plane thereof is broadly used. Light emitted from a light emitting diode formed through growth of the PSS can be scattered due to the protrusions on the surface of the sapphire substrate. Thus, the light emitting diode using the PSS can provide higher light extraction efficiency than a light emitting diode using a general sapphire substrate, thereby providing relatively high external quantum efficiency.